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TAPROBANICA , ISSN 1800–427X. June, 2014. Vol. 06, No. 01: pp. 49–52. © Taprobanica Private Limited, 146, Kendalanda, Homagama, . http://www.sljol.info/index.php/tapro

Marine Mollusc Diversity along the Weiner diversity index. Further analysis was Southwest Coast of Sri Lanka carried out using Cluster and Principle Component Analysis in order to investigate Molluscan as well as class-level variation in habitat with regard to the diversity is highest in the marine environment distribution and abundance of the species (Russell-Hunter, 1983). The current survey data recorded during the study. reveals that Sri Lanka is inhabited by about 240 species of marine molluscs belonging to four of The results for Shannon-Weiner index revealed the seven classes representing marine molluscs a highest diversity at (3.37) and (De Silva, 2006). The study area, along the Negambo (3.36), highest evenness in Negambo southwest coast of Sri Lanka, experiences the (0.051). showed the lowest diversity southwest monsoon from May to September, (2.68) and the lowest evenness (0.035) (Table which has a significant impact on climate and 1). Some shells were found only at a single site. oceanographic conditions in this region. Several species including Amathina tricarinata, Asaphis deflorata, Cantharus undosus, Sites were selected including those associated Chicoreus brunneus, Conus figulinus, with rocky habitats. Such as, isolated rocks on Dentallium sp., Ficus sp., Globularia fluctuata, sandy beaches or scattered continuous rocks Mesodesma glabratum, Phalium decussatum, along the shoreline. Shells were collected along Pharaonella sp., Terebra sp., Tonna luteostoma a 100m line transect parallel to the shoreline, and Vasticardium assimile were only recorded along the backshore. Live specimens during one season (Appendix 1). It was found encountered along each transect were identified that the conditions of the shore differs with the using field guides (Abbott, 1991; Allen, 1998; season, algal species were distinct by season Dyerly et al., 1998; Eye, 1989; Kirthisinghe, (Appendix 2). As for example while there was 1978; Sabelli, 1979; Woodward, 1998), data just one species of alga found on an isolated were recorded and specimens were released. rock at the Panadura site during the monsoon, The field survey was carried-out during the after the monsoon we observed numerous periods of August 2008 to September 2008 and species of algae as well as marine invertebrate December 2008 to March 2009 along the species among the algae such as sp. shores of Chilaw, Negambo, Panadura and Though more data are needed, there were Tangalle (Fig. 1). Observations recorded several species commonly found at all sites include GPS coordinates, types of algae studied (Appendix 1). Of the commonly found present, wave action and slope. GPS points species, there were 12 bivalves and five were obtained using a hand-held GPS receiver. gastropods belonging to 13 families, along with Algal samples were collected and identified one unidentified species. Although these using a field guide (Fish et al., 1989). The species were found at all sites, their abundance frequency of wave action was observed as the varied at the different sites (Fig. 1) and also number of waves striking the breakwater per with regard to the monsoon (Fig. 2–3). The minute. Slope was measured using a clinometer sites were grouped into four clusters at the 25% (Brunton Survey Master 360 LA Sighting). The phenon level and two groups at 100% phenon collected shells were cleaned, separated and level (Figs. 4 A–D). identified using field guides above cited. The identification was further confirmed with The overall results revealed 53 species of identified shell collections at the national gastropods belonging to 29 families, 52 species museum of Sri Lanka (NMSL). Analysis was of bivalves representing 16 families, and one preliminarily carried out using the Shannon- species each representing classes Cephalopoda,

49 TAPROBANICA VOL. 06: NO. 01 MARINE MOLLUSC DIVERSITY ALONG THE SOUTHWEST COAST OF SRI LANKA

Scaphopoda and Polyplacophora. Considering the commonly found species at all four sites, we propose that presence is correlated with different habitat types, except in some special cases such as Duplicaria raphanula and Perna virdis. In these cases other factors may also be at play in determining distributions, including predation pressure, harvest by humans for food or other economic interests, natural dispersal ability, presence of different food resources, near shore current movements, etc. In addition our data suggest that species abundance differs with the monsoonal conditions. Our survey results, while showing some interesting patterns, are preliminary and warrant further investigation.

Table 1: Shannon-Wiener indices; C, Chilaw; N,

Negombo; P, Panadura; T, Tangalle; NE, northeastern monsoon; SW, southwestern monsoon.

N C P T H 3.36 2.83 2.68 3.37 H max 4.19 4.06 4.33 4.32 E 0.051 0.049 0.035 0.045

Figure 2: Relative abundance of selected species among commonly found shells at all four sites.

Figure 3: Relative abundance of selected species Figure 1: Study sites during and after the monsoon period.

50 TAPROBANICA VOL. 06: NO. 01 RUBESINGHE & KRISHNARAJAH, 2014

Eye, K. R., 1989. Shells of the world. In: Bowling, S., M. Brown, R. Dawes, and R. Rees (eds.). Miette Street, London: 179.

Kirthisinghe, P., 1978. Sea shells of Sri Lanka. Tokyo. Charles E. Tuttle co. Inc.: 220.

Russel-Hunter, W. D., 1983. Overview: planetary distribution of and ecological constrains upon the

. In: Wilber, K. M. and W. D. Russel-

Hunter (Eds.). The mollusca. Academic press,

Figure 4: Dendrogram produced from the shell Inc, Florida. abundance data collected from different sites. Sites were grouped according to similarities of Sabelli, B., 1979. Guide to shells, Simon and morphological shell characters; PN, Panadura; NB, Schuster Inc., New York: 512. ; CL, Chilaw; TG, Tangalle; 1, visit 1; 2, visit 2. Woodward, F., 1998. Shells, The Apple press, London: 62. Literature cited Abbott, R. T., 1991. Sea shells of South east Asia, Yoganathan, S., 2005. Monsoonal variations in Tynron Press, Scotland: 145. the distribution of macro invertebrates of the intertidal zone at three locations in Mannar island, Allen, G. R., 1998. Marine life of Malaysia and BSc. Thesis, University of : 51. the Indo-Pacific. In: Nicholes, F. and M. Stachels (eds.). Periplus editions [HK] Ltd, Singapore: 42– Submitted: 23 Nov. 2013, Accepted: 02 April 2014 49. Section Editor: Brenden Holland

De Silva, D., 2006. Current status of 1 2 and ecology of marine molluscs Sri Lanka. The C. H. T. Rubesinghe & S. R. Krishnarajah fauna of Sri Lanka: 274–287. 1 Centre for Environmental Justice, Kuruppu Road, Dyerly, R., P. Fiene-Severns, and M. Severns, 08, Sri Lanka 1998. Tropical sea shells of India and Sri Lanka. E-mail: [email protected] In: Henderson, J. (ed.). Periplus editions [HK] 2 Department of Zoology, Open University of Sri Ltd, Singapore: 61. Lanka, Nawala, Nugegoda, Sri Lanka

Appendix 1: Species found at each site; C, Chilaw; N, Negombo; P, Panadura; T, Tangalle; NE, northeastern monsoon; SW, southwestern monsoon Season SW NE Season SW NE Species Species Site N C P T N C P T Site N C P T N C P T Afrocardium latum Cardiata bicolor

Amathina tricarinata Cardiata variegata

Anadara complanata Cassostrea sp.

Antigona lamellaris Cellana luchuna

Arca bistrigata Cellana radiata

Arca ventricosa Cerastoderma glaucum

Architectonica sp. Chama brassica

Asaphis deflorata Chicoreus brunneus

Astralium sp. Chiton Sp.

Barbatia velata Chlamys sp.

Barbetia virescens Clypidina notata

Bassina calophylla Codakia punctata

Batillaria zonalis Conus figulinus

Bulla amphula Conus sp.

Bursa awatii Crucibulum extinctorium

Calista Chinensis Cymatium retusum

Callista erycina Cymatium spengleri

Cantharus undosus Cyprea moneta

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Season SW NE Season SW NE Species Species Site N C P T N C P T Site N C P T N C P T Cyprea sp. Natica sp.

Dentallium sp. plicata

Diodora mus Nerita textilis

Donax incarnata Oliva sp.

Donax scortum Paphia malabarica

Donax variabilis Periglypta reticulata

Dosinia sp. Petricola lapicida

Drupa musiva Phalium decussatum

Drupa ricinus Pharaonella sp.

Drupella concatenata Pitar hebracea

Duplicaria raphanula Pitar sulfureum

Engina melanozona Pyrene sp.

Eplica versicolor Rhinoclavis sinensis

Euchelus atratus Saccostrea sp.

Ficus sp. Septifer bilocularis

Gastrana polygona Spirula spirula

Globularia fluctuata Spondylus layardi

Gonilia calliglypta Spondylus Tenebrosus

Haliotis squamosa Sunetta scripta

Heliacus variegatus Sunetta sp.

Hipponyx pilosus Tellina sp.

Irus irus Tellinides timorensis

Latona faba Terebra sp.

Lima lima Thais intermedia

Lioconcha fastigiata Thais sp.

Littorina granulata Tonna luteostoma

Littorina undulata Trochus radiatus

Lunulicardia subretusa Turbo sp.

Macroschisma sp. Turritella communis

Mactra turgida Unidentified Il

Mammillia sp. Unidentified lll

Megathura crenulata Unknown l

Meretrix meretrix Vasticardium assimile

Mesodesma glabratum Vasticardium rubicundum

Perna viridis Zeuxis velatus

Nassarius pallidulus

Appendix 2: Field data collected on the study sites; dm, during monsoon; af, after monsoon. Loc. Chilaw Negambo Panadura Tangalle GPS 7o34'22''N, 79o48'8''E 7o13'40''N, 79o50'53''E 6o42'53''N, 79o54’24''E 6o0'44''N, 80o46'4''E Visit 1 Visit 2 Visit 1 Visit 2 Visit 1 Visit 2 Visit 1 Visit 2 Visit & (dm) (am) (dm) (am) (dm) (am) (dm) (am) date 22.8.2008 8.3.2009 22.8.2008 8.3.2009 16.8.2008 27.12.2008 27.9.2008 28.12.2008 Slope / 0 5 7 8 5 6 20 11 7 Wave action/ 8 8 7 8 8 8 6 8 Swells min-1 Gracilaria Ulva Gracilaria Ulva Sargassum Ulva Algae Gracilaria Ulva Ulva - Chaetomorpha Jania Caularpa Halimeda genera Ulva Padina Gelidium Halimida Sargassum Jania Sargassum Padina

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